Shutter based ink jet printing mechanism

ABSTRACT

An ink jet printer uses a shutter based ink jet nozzle. An ink chamber having an oscillating ink pressure is interconnected to a nozzle chamber, which includes a grilled shutter having a first open state permitting the expulsion of ink from the nozzle and a second closed state substantially restricting the expulsion of ink from the nozzle. A shutter activator drives, on demand, the grilled shutter from a closed to open state. A lock is provided to lock the grilled shutter in an open or closed state as required. The shutter activator can be a thermal actuation device having two arms, one arm having a thermal jacket of low thermal conductivity and a thinned portion to increase the travel of the actuator upon activation.

FIELD OF THE INVENTION

The present invention relates to ink jet printing and in particulardiscloses a Shutter Based Ink Jet Printer.

The present invention further relates to the field of drop on demand inkjet printing.

CROSS REFERENCES TO RELATED APPLICATIONS

The following Australian provisional patent applications are herebyincorporated by cross-reference. For the purposes of location andidentification, U.S. patent applications, identified by their U.S.patent application serial numbers (USSN) are listed alongside theAustralian applications from which the US patent applications claim theright of priority.

BACKGROUND OF THE INVENTION

Many different types of printing have been invented, a large number ofwhich are presently in use. The known forms of print have a variety ofmethods for marking the print media with a relevant marking media.Commonly used forms of printing include offset printing, laser printingand copying devices, dot matrix type impact printers, thermal paperprinters, film recorders, thermal wax printers, dye sublimation printersand ink jet printers both of the drop on demand and continuous flowtype. Each type of printer has its own advantages and problems whenconsidering cost, speed, quality, reliability, simplicity ofconstruction and operation etc.

In recent years, the field of ink jet printing, wherein each individualpixel of ink is derived from one or more ink nozzles has becomeincreasingly popular primarily due to its inexpensive and versatilenature.

Many different techniques on ink jet printing have been invented. For asurvey of the field, reference is made to an article by J Moore,“Non-Impact Printing: Introduction and Historical Perspective”, OutputHard Copy Devices, Editors R Dubeck and S Sherr, pages 207 to 220(1988).

Ink Jet printers themselves come in many different types. Theutilisation of a continuous stream ink in ink jet printing appears todate back to at least 1929 wherein U.S. Pat. No. 1,941,001 by Hanselldiscloses a simple form of continuous stream electro-static ink jetprinting.

U.S. Pat. No. 3,596,275 by Sweet also discloses a process of acontinuous ink jet printing including the step wherein the ink jetstream is modulated by a high frequency electrostatic field so as tocause drop separation. This technique is still utilized by severalmanufacturers including Elmjet and Scitex (see also U.S. Pat. No.3,373,437 by Sweet et al)

Piezo-electric ink jet printers are also one form of commonly utilizedink jet printing device. Piezo-electric systems are disclosed by Kyseret. al. in U.S. Pat. No. 3,946,398 (1970) which utilizes a diaphragmmode of operation, by Zolten in U.S. Pat. No. 3,683,212 (1970) whichdiscloses a squeeze mode of operation of a piezo electric crystal,Stemme in U.S. Pat. No. 3,747,120 (1972) discloses a bend mode ofpiezo-electric operation, Howkins in U.S. Pat. No. 4,459,601 discloses aPiezo electric push mode actuation of the ink jet stream and Fischbeckin U.S. Pat. no. 4,584,590 which discloses a sheer mode type ofpiezo-electric transducer element.

Recently, thermal ink jet printing has become an extremely popular formof ink jet printing. The ink jet printing techniques include thosedisclosed by Endo et al in GB 2007162 (1979) and Vaught et al in U.S.Pat. No. 4,490,728. Both the aforementioned references disclosed ink jetprinting techniques rely upon the activation of an electrothermalactuator which results in the creation of a bubble in a constrictedspace, such as a nozzle, which thereby causes the ejection of ink froman aperture connected to the confined space onto a relevant print media.Printing devices utilizing the electro-thermal actuator are manufacturedby manufacturers such as Canon and Hewlett Packard.

As can be seen from the foregoing, many different types of printingtechnologies are available. Ideally, a printing technology should have anumber of desirable attributes. These include inexpensive constructionand operation, high speed operation, safe and continuous long termoperation etc. Each technology may have its own advantages anddisadvantages in the areas of cost, speed, quality, reliability, powerusage, simplicity of construction operation, durability and consumables.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an alternative formof ink jet printing which overcomes some of the aforementioneddifficulties of the prior art through the use of a shutter based ink jetnozzle.

In accordance with a first aspect of the present invention, there isprovided an ink jet printing device comprising an ink chamber having anoscillating ink pressure, a plurality of nozzle apparatuses in fluidcommunication with the ink chamber which include a grilled shutterhaving a first open state permitting the expulsion of ink from thenozzle apparatus and a second closed state substantially restricting theexpulsion of ink from the nozzle chamber, and a shutter activation meansadapted to drive, on demand, the grilled shutter from a first to asecond of these states. Further, the nozzle apparatus includes a lockingmeans adapted to lock the grilled shutter in an open or closed state asrequired. The method of operating the ink jet printing device of thetype in accordance with the present invention comprises the followingsteps:

opening the grilled shutter during a first high pressure period in theink chamber;

utilising the high pressure period and a following low pressure periodfor the expulsion of ink from the nozzle apparatus;

utilising a subsequent high pressure period for the refilling of thenozzle apparatus; and

closing the grilled shutter until such time as further ink is requiredto be expelled from the nozzle apparatus.

Preferably, the ink jet printing device has a shutter activation meansthat comprises a thermocouple device. The thermocouple device consistsof two arms, one arm having a thermal jacket of low thermalconductivity. Advantageously, the arm having no thermal jacket includesa thinned portion adapted to increase the travel of the thermocoupleupon activation.

In the ink jet printing device constructed in accordance with thepresent invention, both the magnitude and frequency of the oscillatingink pressure in the ink chamber can be altered. Preferably, the size andperiod of each cycle can be scaled in accordance with suchpre-calculated factors such as the number of nozzles ejecting ink andthe pressure requirements for nozzle refill with different inks.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of thepresent invention, preferred forms of the invention will now bedescribed, by way of example only, with reference to the accompanyingdrawings which:

FIG. 1 is a perspective view of the top of a print nozzle pair;

FIG. 2 illustrates a partial, cross-sectional view of one shutter andone arm of the thermocouple utilised in the preferred embodiment;

FIG. 3 is a timing diagram illustrating the operation of the preferredembodiment;

FIG. 4 illustrates an exploded perspective view of a pair of printnozzles constructed in accordance with the preferred embodiment.

FIG. 5 provides a legend of the materials indicated in FIGS. 6 to 20;and

FIG. 6 to FIG. 20 illustrate sectional views of the manufacturing stepsin one form of construction of an ink jet printhead nozzle.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

The preferred embodiment utilises an ink reservoir with oscillating inkpressure and a shutter activated by a thermal actuator to eject drops ofink.

Turning now to FIG. 1, there is illustrated two ink nozzle arrangements20, 21 as constructed in accordance with the preferred embodiment. Theink nozzle arrangement 20 is shown in an open position with the inknozzle arrangement 21 shown in a closed position. The ink nozzlearrangement of FIG. 1 can be constructed as part of a large array ofnozzles or print heads on a silicon wafer utilising micro-electromechanical technologies (MEMS). For a general introduction to amicro-electro mechanical system (MEMS) reference is made to standardproceedings in this field such as the proceeding of the SPIE(International Society for Optical Engineering) including volumes 2642and 2882 which contain the proceedings of recent advances andconferences in this field.

In FIG. 1, each of the ink nozzle arrangements 20, 21 covers an inknozzle eg. 22 from which ejection of ink occurs when the ink nozzlearrangement is in an open state and the pressure wave is at a maximum.

Each of the ink nozzle arrangements of FIG. 1 utilises a thermocoupleactuator device 9 having two arms. The ink nozzle arrangement 20utilises arms 24, 25 and the ink apparatus 21 utilising thermocouplearms 26, 27. The thermocouple arms 24, 25 are responsible for movementof a grated shutter device within a shutter cage 29.

Referring now to FIG. 2, there is illustrated the thermocouple arms 24,25 and shutter 30 of FIG. 1 without the cage. The shutter 30 includes anumber of apertures 31 for the passage of ink through the shutter 30when the shutter is in an open state. The thermocouple arms 24, 25 areresponsible for movement of the shutter 30 upon activation of thethermocouple via means of an electric current flowing through bondingpads 32, 33 (FIG. 1). The thermal actuator of FIG. 2 operates alongsimilar principles to that disclosed in the aforementioned proceedingsby the authors J. Robert Reid, Victor M. Bright and John. H. Comtoiswith a number of significant differences in operation which will now bediscussed. The arm 24 can comprise an inner core of poly-siliconsurrounded by an outer jacket of thermally insulating material. Thecross-section of the arm 24 is illustrated in FIG. 2 and includes theinner core 40 and the outer core 41.

It would be appreciated by a person skilled in the art that numerousvariations and/or modifications may be made to the present invention asshown in the specific embodiment without departing from the spirit orscope of the invention as broadly described. The present embodiment is,therefore, to be considered in all respects to be illustrative and notrestrictive.

A current is passed through the two arms 24, 25 via bonding pads 32, 33.The arm 24 includes an inner resistive element 40, preferably comprisingpolysilicon or the like which heats up upon a current being passedthrough it. The thermal jacket 41 is provided to isolate the inner core40 from the ink chamber 11 in which the arms 24, 25 are immersed.

It should be noted that the arm 24 contains a thermal jacket whereas thearm 25 does not include a thermal jacket. Hence, the arm 25 will begenerally cooler than the arm 24 and undergo a different rate of thermalexpansion. The two arms acting together to form a thermal actuator. Thethermocouple comprising arms 24, 25 results in movement of the shutter30 generally in the direction 34 upon a current being passed through thetwo arms. Importantly, the arm 25 includes a thinned portion 36 (inFIG. 1) which amplifies the radial movement of shutter 30 around acentral axis near the bonding pads 32, 33 (in FIG. 1). This results in a“magnification” of the rotational effects of activation of thethermocouple, resulting in an increased movement of the shutter 30. Thethermocouples 24, 25 can be activated to move the shutter 30 from theclosed position as illustrated generally 21 in FIG. 1 to an openposition as illustrated 20 in FIG. 1.

Returning now to FIG. 1 a second thermocouple actuator 50 is alsoprovided having first and second arms 51, 52. The actuator 50 operateson the same physical principals as the arm associated with the shuttersystem 30. The arm 50 is designed to be operated so as to lock theshutter 30 in an open or closed position. The arm 50 locking the shutter30 in an open position Is illustrated in FIG. 1. When in a closedposition, the arm 50 locks the shutter by means of engagement of knob 38with a cavity on shutter 30 (not shown). After a short period, theshutter 30 is deactivated, and the hot arm 24 (FIG. 2) of the actuatorbegins to cool.

An example timing diagram of operation of each ink nozzle arrangementwill now be described. In FIG. 3 there is illustrated generally 55 afirst pressure plot which illustrates the pressure fluctuation around anambient pressure within the ink chamber (11 of FIG. 2) as a result ofthe driving of the piezo-electric actuator in a substantially sinusoidalmanner. The pressure fluctuation 70 is also substantially sinusoidal innature and the printing cycle is divided into four phases being a dropformation phase 71, a drop separation phase 72, a drop refill phase 73and a drop settling phase 74.

Also shown in FIG. 3 are clock timing diagrams 56 and 57. The firstdiagram 56 illustrates the control pulses received by the shutterthermal actuator of a single ink nozzle so as to open and close theshutter. The second clock timing diagram 57 is directed to the operationof the second thermal actuator or latch (eg. 50 of FIG. 1).

At the start of the drop formation phase 71 when the pressure 70 withinthe ink chamber is going from a negative pressure to a positivepressure, the latch 50 is actuated 59 to an open state. Subsequently,the shutter is also actuated 60 so that it also moves from a closed toan open position. Next, the latch 50 is deactivated 61 thereby lockingthe shutter in an open position with the head 63 (FIG. 1) of the latch50 locking against one side of the shutter 30. Simultaneously, theshutter 30 is deactivated 62 to reduce the power consumption in thenozzle.

As the ink chamber and ink nozzle are in a positive pressure state atthis time, the ink meniscus will be expanding out of the ink nozzle.

Subsequently, the drop separation phase 72 is entered wherein thechamber undergoes a negative pressure causing a portion of the flowingink flowing out of the ink nozzle back into the chamber. This rapid flowcauses ink bubble separation from the main body of ink. The ink bubbleor jet then passes to the print media while the surface meniscus of theink collapses back into the ink nozzle. Subsequently, the pressure cycleenters the drop refill stage 73 with the shutter still open with apositive pressure cycle experienced. This causes rapid refilling of theink chamber. At the end of the drop re-filling stage, the latch 50 isopened 63 causing the now cold shutter to spring back to a closedposition. Subsequently, the latch is closed 64 locking the shutter inthe closed position, thereby completing one cycle of printing. Theclosed shutter allows a drop settling stage 74 to be entered whichallows for the dissipation of any resultant ringing or transient in theink meniscus position while the shutter is closed. At the end of thedrop settling stage, the state has returned to the start of the dropformation stage 71 and another drop can be ejected from the ink nozzle.

Of course, a number of refinements of operation are possible. In a firstrefinement, the pressure wave oscillation which is shown to be aconstant oscillation in magnitude and frequency can be altered in bothrespects. The size and period of each cycle can be scaled in accordancewith such pre-calculated factors such as the number of nozzles ejectingink and the tuned pressure requirements for nozzle refill with differentinks. Further, the clock periods of operation can be scaled to take intoaccount differing effects such as actuation speeds etc.

Turning now to FIG. 4, there is illustrated 80 an exploded perspectiveview of one form of construction of the ink nozzle pair 20, 21 of FIG.1.

The ink jet nozzles are constructed on a buried boron-doped layer 81 ofa silicon wafer 71 which includes fabricated nozzle rims, e.g. 83 whichform part of the layer 81 and limit any hydrophilic spreading of themeniscus on the bottom end of the layer 81. The nozzle rim, e.g. 83 canbe dispensed with when the bottom surface of layer 81 is suitablytreated with a hydrophobosizing process.

On top of the wafer 82 is constructed a CMOS layer 85 which contains allthe relevant circuitry required for driving of the two nozzles. ThisCMOS layer is finished with a silicon dioxide layer 86. Both the CMOSlayer 85 and the silicon dioxide 86 include triangular apertures 87 and88 allowing for the fluid communication with the nozzle ports, e.g. 84.

On top of the SiO₂ layer 86 are constructed the various shutter layers90 to 92. A first shutter layer 90 is constructed from a first layer ofpolysilicon and comprises the shutter and actuator mechanisms. A secondshutter layer 91 can be constructed from a polymer, for example,polyamide and acts as a thermal insulator on one arm of each of thethermocouple devices. A final covering cage layer 92 is constructed froma second layer of polysilicon.

The construction of the nozzles 80 relies upon standard semi-conductorfabrication processes and MEMS process known to those skilled in theart. For a general introduction to a micro-electro mechanical system(MEMS) reference is made to standard proceedings in this field includingthe proceedings of the SPIE (International Society for OpticalEngineering), volumes 2642 and 2882 which contain the proceedings forrecent advances and conferences in this field.

One form of construction of nozzle arrangement 80 would be to utilise asilicon wafer containing a boron doped epitaxial layer which forms thefinal layer 81. The silicon wafer layer 82 is formed naturally above theboron doped epitaxial 81. On top of this layer is formed the layer 85with the relevant CMOS circuitry etc. being constructed in this layer.The apertures 87, 88 can be formed within the layers by means of plasmaetching utilising an appropriate mask. Subsequently, these layers can bepassivated by means of a nitride covering and then filled with asacrificial material such as glass which will be subsequently etched. Asacrificial material with an appropriate mask can also be utilised as abase for the moveable portions of the layer 90 which are again depositedutilising appropriate masks. Similar procedures can be carried out forthe layers 91, 92. Next, the wafer can be thinned by means of backetching of the wafer to the boron doped epitaxial layer 91 which isutilised as an etchant stop. Subsequently, the nozzle rims and nozzleapertures can be formed and the internal portions of the nozzle chamberand other layers can be sacrificially etched away releasing the shutterstructure. Subsequently, the wafer can be diced into appropriate printheads attached to an ink chamber wafer and tested for operational yield.

Of course, many other materials can be utilised to form the constructionof each layer. For example, the shutter and actuators could beconstructed from tantalum or a number of other substances known to thoseskilled in the art of construction of MEMS devices.

It will be evident to the person skilled in the art, that large arraysof ink jet nozzle pairs can be constructed on a single wafer and ink jetprint heads can be attached to a corresponding ink chamber for drivingof ink through the print head, on demand, to the required print media.Further, normal aspects of (MEMS) construction such as the utilisationof dimples to reduce the opportunity for stiction, while notspecifically disclosed in the current embodiment would be obviouslyutilised as means to improve yield and operation of the shutter deviceas constructed in accordance with the preferred embodiment.

One form of detailed manufacturing process which can be used tofabricate monolithic ink jet print heads operating in accordance withthe principles taught by the present embodiment can proceed utilizingthe following steps:

1. Using a double sided polished wafer deposit 3 microns of epitaxialsilicon heavily doped with boron.

2. Deposit 10 microns of n/n+ epitaxial silicon. Note that the epitaxiallayer is substantially thicker than required for CMOS. This is becausethe nozzle chambers are crystallographically etched from this layer.This step is shown in FIG. 6. FIG. 5 is a key to representations ofvarious materials in these manufacturing diagrams, and those of othercross referenced ink jet configurations. For clarity, these diagrams maynot be to scale, and may not represent a cross section though any singleplane of the nozzle.

3. Plasma etch the epitaxial silicon with approximately 90 degreesidewalls using MEMS Mask 1. This mask defines the nozzle cavity. Theetch is timed for a depth approximately equal to the epitaxial silicon(10 microns), to reach the boron doped silicon buried layer. This stepis shown in FIG. 7.

4. Deposit 10 microns of low stress sacrificial oxide. Planarize down tosilicon using CMP. The sacrificial material temporarily fills the nozzlecavity. This step is shown in FIG. 8.

5. Begin fabrication of the drive transistors, data distribution, andtiming circuits using a CMOS process. The MEMS processes which form themechanical components of the inkjet are interleaved with the CMOS devicefabrication steps. The example given here is of a 1 micron, 2 poly, 1metal retrograde P-well process. The mechanical components are formedfrom the CMOS polysilicon layers. For clarity, the CMOS activecomponents are omitted.

6. Grow the field oxide using standard LOCOS techniques to a thicknessof 0.5 microns. As well as the isolation between transistors, the fieldoxide is used as a MEMS sacrificial layer, so inkjet mechanical detailsare incorporated in the active area mask. The MEMS features of this stepare shown in FIG. 9.

7. Perform the PMOS field threshold implant. The MEMS fabrication has noeffect on this step except in calculation of the total thermal budget.

8. Perform the retrograde P-well and NMOS threshold adjust implants. TheMEMS fabrication has no effect on this step except in calculation of thetotal thermal budget.

9. Perform the PMOS N-tub deep phosphorus punchthrough control implantand shallow boron implant. The MEMS fabrication has no effect on thisstep except in calculation of the total thermal budget.

10. Deposit and etch the first polysilicon layer. As well as gates andlocal connections, this layer includes the lower layer of MEMScomponents. This includes the shutter, the shutter actuator, and thecatch actuator. It is preferable that this layer be thicker than thenormal CMOS thickness. A polysilicon thickness of 1 micron can be used.The MEMS features of this step are shown in FIG. 10.

11. Perform the NMOS lightly doped drain (LDD) implant. This process isunaltered by the inclusion of MEMS in the process flow.

12. Perform the oxide deposition and RIE etch for polysilicon gatesidewall spacers. This process is unaltered by the inclusion of MEMS inthe process flow.

13. Perform the NMOS source/drain implant. The extended high temperatureanneal time to reduce stress in the two polysilicon layers must be takeninto account in the thermal budget for diffusion of this implant.Otherwise, there is no effect from the MEMS portion of the chip.

14. Perform the PMOS source/drain implant. As with the NMOS source/drainimplant, the only effect from the MEMS portion of the chip is on thermalbudget for diffusion of this implant.

15. Deposit 1.3 micron of glass as the first interlevel dielectric andetch using the CMOS contacts mask. The CMOS mask for this level alsocontains the pattern for the MEMS inter-poly sacrificial oxide. The MEMSfeatures of this step are shown in FIG. 11.

16. Deposit and etch the second polysilicon layer. As well as CMOS localconnections, this layer includes the upper layer of MEMS components.This includes the grill and the catch second layer (which exists toensure that the catch does not ‘slip off’ the shutter. A polysiliconthickness of 1 micron can be used. The MEMS features of this step areshown in FIG. 12.

17. Deposit 1 micron of glass as the second interlevel dielectric andetch using the CMOS via 1 mask. The CMOS mask for this level alsocontains the pattern for the MEMS actuator contacts.

18. Deposit and etch the metal layer. None of the metal appears in theMEMS area, so this step is unaffected by the MEMS process additions.However, all required annealing of the polysilicon should be completedbefore this step. The MEMS features of this step are shown in FIG. 13.

19. Deposit 0.5 microns of silicon nitride (Si3N4) and etch using MEMSMask 2. This mask defines the region of sacrificial oxide etch performedin step 24. The silicon nitride aperture is substantially undersized, asthe sacrificial oxide etch is isotropic. The CMOS devices must belocated sufficiently far from the MEMS devices that they are notaffected by the sacrificial oxide etch. The MEMS features of this stepare shown in FIG. 14.

20. Mount the wafer on a glass blank and back-etch the wafer using KOHwith no mask. This etch thins the wafer and stops at the buried borondoped silicon layer. The MEMS features of this step are shown in FIG.15.

21. Plasma back-etch the boron doped silicon layer to a depth of 1micron using MEMS Mask 3. This mask defines the nozzle rim. The MEMSfeatures of this step are shown in FIG. 16.

22. Plasma back-etch through the boron doped layer using MEMS Mask 4.This mask defines the nozzle, and the edge of the chips. At this stage,the chips are separate, but are still mounted on the glass blank. TheMEMS features of this step are shown in FIG. 17.

23. Detach the chips from the glass blank. Strip the adhesive. This stepis shown in FIG. 18.

24. Etch the sacrificial oxide using vapor phase etching (VPE) using ananhydrous HF/methanol vapor mixture. The use of a dry etch avoidsproblems with stiction. This step is shown in FIG. 19.

25. Mount the print heads in their packaging, which may be a moldedplastic former incorporating ink channels which supply different colorsof ink to the appropriate regions of the front surface of the wafer. Thepackage also includes a piezoelectric actuator attached to the rear ofthe ink channels. The piezoelectric actuator provides the oscillatingink pressure required for the ink jet operation.

26. Connect the print heads to their interconnect systems.

27. Hydrophobize the front surface of the print heads.

28. Fill the completed print heads with ink and test them. A fillednozzle is shown in FIG. 20.

The presently disclosed ink jet printing technology is potentiallysuited to a wide range of printing systems including: colour andmonochrome office printers, short run digital printers, high speeddigital printers, offset press supplemental printers, low cost scanningprinters, high speed pagewidth printers, notebook computers with inbuiltpagewidth printers, portable colour and monochrome printers, colour andmonochrome copiers, colour and monochrome facsimile machines, combinedprinter, facsimile and copying machines, label printers, large formatplotters, photograph copiers, printers for digital photographic‘minilabs’, video printers, PhotoCD printers, portable printers forPDAs, wallpaper printers, indoor sign printers, billboard printers,fabric printers, camera printers and fault tolerant commercial printerarrays.

Ink Jet Technologies

The embodiments of the invention use an ink jet printer type device. Ofcourse many different devices could be used. However presently popularink jet printing technologies are unlikely to be suitable.

The most significant problem with thermal inkjet is power consumption.This is approximately 100 times that required for high speed, and stemsfrom the energy-inefficient means of drop ejection. This involves therapid boiling of water to produce a vapor bubble which expels the ink.Water has a very high heat capacity, and must be superheated in thermalinkjet applications. This leads to an efficiency of around 0.02%, fromelectricity input to drop momentum (and increased surface area) out.

The most significant problem with piezoelectric inkjet is size and cost.Piezoelectric crystals have a very small deflection at reasonable drivevoltages, and therefore require a large area for each nozzle. Also, eachpiezoelectric actuator must be connected to its drive circuit on aseparate substrate. This is not a significant problem at the currentlimit of around 300 nozzles per print head, but is a major impediment tothe fabrication of pagewide print heads with 19,200 nozzles.

Ideally, the inkjet technologies used meet the stringent requirements ofin-camera digital color printing and other high quality, high speed, lowcost printing applications. To meet the requirements of digitalphotography, new inkjet technologies have been created. The targetfeatures include:

low power (less than 10 Watts) high resolution capability (1,600 dpi ormore)

photographic quality output

low manufacturing cost

small size (pagewidth times minimum cross section)

high speed (<2 seconds per page).

All of these features can be met or exceeded by the inkjet systemsdescribed below with differing levels of difficulty. 45 different inkjettechnologies have been developed by the Assignee to give a wide range ofchoices for high volume manufacture. These technologies form part ofseparate applications assigned to the present Assignee as set out in thetable below.

The inkjet designs shown here are suitable for a wide range of digitalprinting systems, from battery powered one-time use digital cameras,through to desktop and network printers, and through to commercialprinting systems

For ease of manufacture using standard process equipment, the print headis designed to be a monolithic 0.5 micron CMOS chip with MEMS postprocessing. For color photographic applications, the print head is 100mm long, with a width which depends upon the inkjet type. The smallestprint head designed is IJ38, which is 0.35 mm wide, giving a chip areaof 35 square mm. The print heads each contain 19,200 nozzles plus dataand control circuitry.

Ink is supplied to the back of the print head by injection moldedplastic ink channels. The molding requires 50 micron features, which canbe created using a lithographically micromachined insert in a standardinjection molding tool. Ink flows through holes etched through the waferto the nozzle chambers fabricated on the front surface of the wafer. Theprint head is connected to the camera circuitry by tape automatedbonding.

CROSS-RELATED APPLICATIONS

The following table is a guide to cross-referenced patent applicationsfiled concurrently herewith and discussed hereinafter with the referencebeing utilized in subsequent tables when referring to a particular case:

Docket Reference Title IJ01US IJ01 Radiant Plunger Ink Jet PrinterIJ02US IJ02 Electrostatic Ink Jet Printer IJ03US IJ03 PlanarThermoelastic Bend Actuator Ink Jet IJ04US IJ04 Stacked ElectrostaticInk Jet Printer IJ05US IJ05 Reverse Spring Lever Ink Jet Printer IJ06USIJ06 Paddle Type Ink Jet Printer IJ07US IJ07 Permanent MagnetElectromagnetic Ink Jet Printer IJ08US IJ08 Planar Swing GrillElectromagnetic Ink Jet Printer IJ09US IJ09 Pump Action Refill Ink JetPrinter IJ10US IJ10 Pulsed Magnetic Field Ink Jet Printer IJ11US IJ11Two Plate Reverse Firing Electromagnetic Ink Jet Printer IJ12US IJ12Linear Stepper Actuator Ink Jet Printer IJ13US IJ13 Gear Driven ShutterInk Jet Printer IJ14US IJ14 Tapered Magnetic Pole Electromagnetic InkJet Printer IJ15US IJl5 Linear Spring Electromagnetic Grill Ink JetPrinter IJ16US IJ16 Lorenz Diaphragm Electromagnetic Ink Jet PrinterIJ17US IJ17 PTFE Surface Shooting Shuttered Oscillating Pressure Ink JetPrinter IJ18US IJ18 Buckle Grip Oscillating Pressure Ink Jet PrinterIJ19US IJ19 Shutter Based Ink Jet Printer IJ20US IJ20 Curling CalyxThermoelastic Ink Jet Printer IJ21US IJ21 Thermal Actuated Ink JetPrinter IJ22U5 IJ22 Iris Motion Ink Jet Printer IJ23US IJ23 DirectFiring Thermal Bend Actuator Ink Jet Printer IJ24U5 IJ24 Conductive PTFEBen Activator Vented Ink Jet Printer IJ25U5 IJ25 Magnetostrictive InkJet Printer IJ26U5 IJ26 Shape Memory Alloy Ink Jet Printer IJ27U5 IJ27Buckle Plate Ink Jet Printer IJ28U5 IJ28 Thermal Elastic Rotary ImpellerInk Jet Printer IJ29U5 IJ29 Thermoelastic Bend Actuator Ink Jet PrinterIJ30US IJ30 Thermoelastic Bend Actuator Using PTFE and Corrugated CopperInk Jet Printer IJ31US IJ31 Bend Actuator Direct Ink Supply Ink JetPrinter IJ32U5 IJ32 A High Young's Modulus Thermoelastic Ink Jet PrinterIJ33U5 IJ33 Thermally actuated slotted chamber wall ink jet printerIJ34U5 IJ34 Ink Jet Printer having a thermal actuator comprising anexternal coiled spring IJ35US IJ35 Trough Container Ink Jet PrinterIJ36US IJ36 Dual Chamber Single Vertical Actuator Ink Jet IJ37U5 IJ37Dual Nozzle Single Horizontal Fulcrum Actuator Ink Jet IJ38U5 IJ38 DualNozzle Single Horizontal Actuator Ink Jet IJ39U5 IJ39 A single bendactuator cupped paddle ink jet printing device IJ40US IJ40 A thermallyactuated ink jet printer having a series of thermal actuator unitsIJ41US IJ41 A thermally actuated ink jet printer including a taperedheater element IJ42U5 IJ42 Radial Back-Curling Thermoelastic Ink JetIJ43US IJ43 Inverted Radial Back-Curling Thermoelastic Ink Jet IJ44USIJ44 Surface bend actuator vented ink supply ink jet printer IJ45US IJ45Coil Actuated Magnetic Plate Ink Jet Printer

Tables of Drop-on-Demand Inkjets

Eleven important characteristics of the fundamental operation ofindividual inkjet nozzles have been identified. These characteristicsare largely orthogonal, and so can be elucidated as an elevendimensional matrix. Most of the eleven axes of this matrix includeentries developed by the present assignee.

The following tables form the axes of an eleven dimensional table ofinkjet types.

Actuator mechanism (18 types)

Basic operation mode (7 types)

Auxiliary mechanism (8 types)

Actuator amplification or modification method (17 types)

Actuator motion (19 types)

Nozzle refill method (4 types)

Method of restricting back-flow through inlet (10 types)

Nozzle clearing method (9 types)

Nozzle plate construction (9 types)

Drop ejection direction (5 types)

Ink type (7 types)

The complete eleven dimensional table represented by these axes contains36.9 billion possible configurations of inkjet nozzle. While not all ofthe possible combinations result in a viable inkjet technology, manymillion configurations are viable. It is clearly impractical toelucidate all of the possible configurations. Instead, certain inkjettypes have been investigated in detail. These are designated IJ01 toIJ45 above.

Other inkjet configurations can readily be derived from these 45examples by substituting alternative configurations along one or more ofthe 11 axes. Most of the IJ01 to IJ45 examples can be made into inkjetprint heads with characteristics superior to any currently availableinkjet technology.

Where there are prior art examples known to the inventor, one or more ofthese examples are listed in the examples column of the tables below.The IJ01 to IJ45 series are also listed in the examples column. In somecases, a printer may be listed more than once in a table, where itshares characteristics with more than one entry.

Suitable applications include: Home printers, Office network printers,Short run digital printers, Commercial print systems, Fabric printers,Pocket printers, Internet WWW printers, Video printers, Medical imaging,Wide format printers, Notebook PC printers, Fax machines, Industrialprinting systems, Photocopiers, Photographic minilabs etc.

The information associated with the aforementioned 11 dimensional matrixare set out in the following tables.

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) ActuatorMechanism Description Advantages Disadvantages Examples Thermal Anelectrothermal heater heats the Large force generated High power CanonBubblejet bubble ink to above boiling point, Simple construction Inkcarrier limited to water 1979 Endo et al GB transferring significantheat to the No moving parts Low efficiency patent 2,007,162 aqueous ink.A bubble nucleates and Fast operation High temperatures required Xeroxheater-in-pit quickly forms, expelling the ink. Small chip area requiredfor High mechanical stress 1990 Hawkins et al The efficiency of theprocess is low, actuator Unusual materials required USP 4,899,181 withtypically less than 0.05% of the Large drive transistors Hewlett-PackardTIJ electrical energy being transformed Cavitation causes actuatorfailure 1982 Vaught et al into kinetic energy of the drop. Kogationreduces bubble formation USP 4,490,728 Large print heads are difficultto fabricate Piezoelectric A piezoelectric crystal such as lead Lowpower consumption Very large area required for actuator Kyser et al USPlanthanum zirconate (PZT) is Many ink types can be used Difficult tointegrate with electronics 3,946,398 electrically activated, and eitherFast operation High voltage drive transistors required Zoltan USPexpands, shears, or bends to apply High efficiency Full pagewidth printheads impractical 3,683,212 pressure to the ink, ejecting drops. due toactuator size 1973 Stemme USP Requires electrical poling in high field3,747,120 strengths during manufacture Epson Stylus Tektronix IJ04Electro- An electric field is used to activate Low power consumption Lowmaximum strain (approx. 0.01%) Seiko Epson, Usui et strictiveelectrostriction in relaxor materials Many ink types can be used Largearea required for actuator due to all JP 253401/96 such as leadlanthanum zirconate Low thermal expansion low strain IJ04 titanate(PLZT) or lead magnesium Electric field strength Response speed ismarginal (˜10 μs) niobate (PMN). required (approx. 3.5 V/μm) Highvoltage drive transistors required can be generated without Fullpagewidth print heads impractical difficulty due to actuator size Doesnot require electrical poling Ferroelectric An electric field is used toinduce a Low power consumption Difficult to integrate with electronicsIJ04 phase transition between the Many ink types can be used Unusualmaterials such as PLZSnT are antiferroelectric (AFE) and Fast operation(<1 μs) required ferroelectric (FE) phase. Perovskite Relatively highlongitudinal Actuators require a large area materials such as tinmodified lead strain lanthanum zirconate titanate High efficiency(PLZSnT) exhibit large strains of up Electric field strength of to 1%associated with the AFE to FE around 3 V/μm can be phase transition.readily provided Electrostatic Conductive plates are separated by a Lowpower consumption Difficult to operate electrostatic IJ02, IJ04 platescompressible or fluid dielectric Many ink types can be used devices inan aqueous environment (usually air). Upon application of a Fastoperation The electrostatic actuator will normally voltage, the platesattract each other need to be separated from the ink and displace ink,causing drop Very large area required to achieve ejection. Theconductive plates may high forces be in a comb or honeycomb High voltagedrive transistors may be structure, or stacked to increase the requiredsurface area and therefore the force. Full pagewidth print heads are notcompetitive due to actuator size Electrostatic A strong electric fieldis applied to Low current consumption High voltage required 1989 Saitoet al, USP pull on ink the ink, whereupon electrostatic Low temperatureMay be damaged by sparks due to air 4,799,068 attraction accelerates theink towards breakdown 1989 Miura et al, the print medium. Required fieldstrength increases as the USP 4,810,954 drop size decreases Tone-jetHigh voltage drive transistors required Electrostatic field attractsdust Permanent An electromagnet directly attracts a Low powerconsumption Complex fabrication IJ07, IJ10 magnet permanent magnet,displacing ink Many ink types can be used Permanent magnetic materialsuch as electro- and causing drop ejection. Rare earth Fast operationNeodymium Iron Boron (NdFeB) magnetic magnets with a field strengtharound High efficiency required. 1 Tesla can be used. Examples are: Easyextension from single High local currents required Samarium Cobalt(SaCo) and nozzles to pagewidth print Copper metalization should be usedfor magnetic materials in the heads long electromigration lifetime andlow neodymium iron boron family resistivity (NdFeB, NdDyFeBNb, NdDyFeB,Pigmented inks are usually infeasible etc) Operating temperature limitedto the Curie temperature (around 540 K.) Soft magnetic A solenoidinduced a magnetic field Low power consumption Complex fabrication IJ01,IJ05, IJ08, IJ10 core electro- in a soft magnetic core or yoke Many inktypes can be used Materials not usually present in a IJ12, IJ14, IJ15,IJ17 magnetic fabricated from a ferrous material Fast operation CMOS fabsuch as NiFe, CoNiFe, or such as electroplated iron alloys such Highefficiency CoFe are required as CoNiFe [1], CoFe, or NiFe alloys. Easyextension from single High local currents required Typically, the softmagnetic material nozzles to pagewidth print Copper metalization shouldbe used for is in two parts, which are normally heads longelectromigration lifetime and low held apart by a spring. When theresistivity solenoid is actuated, the two parts Electroplating isrequired attract, displacing the ink. High saturation flux density isrequired (2.0-2.1 T is achievable with CoNiFe [1]) Magnetic The Lorenzforce acting on a current Low power consumption Force acts as a twistingmotion IJ06, IJ11, IJ13, IJ16 Lorenz force carrying wire in a magneticfield is Many ink types can be used Typically, only a quarter of theutilized. Fast operation solenoid length provides force in a This allowsthe magnetic field to be High efficiency useful direction suppliedexternally to the print head, Easy extension from single High localcurrents required for example with rare earth nozzles to pagewidth printCopper metalization should be used for permanent magnets. heads longelectromigration lifetime and low Only the current carrying wire needresistivity be fabricated on the print-head, Pigmented inks are usuallyinfeasible simplifying materials requirements. Magneto- The actuatoruses the giant- Many ink types can be used Force acts as a twistingmotion Fischenbeck, USP striction magnetostrictive effect of materialsFast operation Unusual materials such as Terfenol-D 4,032,929 such asTerfenol-D (an alloy of Easy extension from single are required IJ25terbium, dysprosium and iron nozzles to pagewidth print High localcurrents required developed at the Naval Ordnance heads Coppermetalization should be used for Laboratory, hence Ter-Fe-NOL). For Highforce is available long electromigration lifetime and low bestefficiency, the actuator should Pre-stressing may be required bepre-stressed to approx. 8 MPa. Surface Ink under positive pressure isheld in Low power consumption Requires supplementary force to effectSilverbrook, BP 077 1 tension a nozzle by surface tension. The Simpleconstruction drop separation 658 A2 and reduction surface tension of theink is reduced No unusual materials Requires special ink surfactantspatent applications below the bubble threshold, causing required infabrication Speed may be limited by surfactant the ink to egress fromthe nozzle. High efficiency properties extension from single nozzles topagewidth print heads Viscosity The ink viscosity is locally reducedSimple construction Requires supplementary force to effect Silverbrook,EP 0771 reduction to select which drops are to be No unusual materialsdrop separation 658 A2 and related ejected. A viscosity reduction can berequired in fabrication Requires special ink viscosity patentapplications achieved electrothermally with most Easy extension fromsingle properties inks, but special inks can be nozzles to pagewidthprint High speed is difficult to achieve engineered for a 100:1viscosity heads Requires oscillating ink pressure reduction. A hightemperature difference (typically 80 degrees) is required Acoustic Anacoustic wave is generated and Can operate without a Complex drivecircuitry 1993 Hadimioglu et focussed upon the drop ejection nozzleplate Complex fabrication al, EUP 550,192 region. Low efficiency 1993Elrod et al, EUP Poor control of drop position 572 ,220 Poor control ofdrop volume Thermoelastic An actuator which relies upon Low powerconsumption Efficient aqueous operation requires a IJ03, IJ09, IJ17,IJ18 bend actuator differential thermal expansion upon Many ink typescan be used thermal insulator on the hot side IJ19, IJ20, IJ21, IJ22Joule heating is used. Simple planar fabrication Corrosion preventioncan be difficult IJ23, IJ24, IJ27, IJ28 Small chip area required forPigmented inks may be infeasible, as IJ29, IJ30, IJ31, IJ32 eachactuator pigment particles may jam the bend IJ33, IJ34, IJ35, IJ36 Fastoperation actuator IJ37, IJ38 ,IJ39, IJ40 High efficiency IJ41 CMOScompatible voltages and currents Standard MEMS processes can be usedEasy extension from single nozzles to pagewidth print heads High CTE Amaterial with a very high High force can be generated Requires specialmaterial (e.g. PTFE) IJ09, IJ17, IJ18, IJ20 thermoelastic coefficient ofthermal expansion PTFE is a candidate for low Requires a PTFE depositionprocess, IJ21, IJ22, IJ23, IJ24 actuator (CTE) such as dielectricconstant which is not yet standard in ULSI fabs IJ27, IJ28, IJ29, IJ30polytetrafluoroethylene (PTFE) is insulation in ULSI PTFE depositioncannot be followed IJ31, IJ42, IJ43, IJ44 used. As high CTE materialsare Very low power with high temperature (above 350° C.) usuallynon-conductive, a heater consumption processing fabricated from aconductive Many ink types can be used Pigmented inks may be infeasible,as material is incorporated. A 50 μm Simple planar fabrication pigmentparticles may jam the bend long PTFE bend actuator with Small chip arearequired for actuator polysilicon heater and 15 mW power each actuatorinput can provide 180 μN force and Fast operation 10 μm deflection.Actuator motions High efficiency include: CMOS compatible voltages 1)Bend and currents 2) Push Easy extension from single 3) Buckle nozzlesto pagewidth print 4) Rotate heads Conductive A polymer with a highcoefficient of High force can be generated Requires special materialsIJ24 polymer thermal expansion (such as PTFE) is Very low powerdevelopment (High CTE conductive thermoelastic doped with conductingsubstances to consumption polymer) actuator increase its conductivity toabout 3 Many ink types can be used Requires a PTFE deposition process,orders of magnitude below that of Simple planar fabrication which is notyet standard in ULSI fabs copper. The conducting polymer Small chip arearequired for PTFE deposition cannot be followed expands when resistivelyheated. each actuator with high temperature (above 350° C.) Examples ofconducting dopants Fast operation processing include: High efficiencyEvaporation and CVD deposition 1) Carbon nanotubes CMOS compatiblevoltages techniques cannot be used 2) Metal fibers and currentsPigmented inks may be infeasible, as 3) Conductive polymers such as Easyextension from single pigment particles may jam the bend  dopedpolythiophene nozzles to pagewidth print actuator 4) Carbon granulesheads Shape memory A shape memory alloy such as TiNi High force isavailable Fatigue limits maximum number of IJ26 alloy (also known asNitinol - Nickel (stresses of hundreds of cycles Titanium alloydeveloped at the MPa) Low strain (1%) is required to extend NavalOrdnance Laboratory) is Large strain is available fatigue resistancethermally switched between its weak (more than 3%) Cycle rate limited byheat removal martensitic state and its high High corrosion resistanceRequires unusual materials (TiNi) stiffness austenic state. The shape ofSimple construction The latent heat of transformation must the actuatorin its martensitic state is Easy extension from single be provideddeformed relative to the austenic nozzles to pagewidth print Highcurrent operation shape. The shape change causes heads Requirespre-stressing to distort the ejection of a drop. Low voltage operationmartensitic state Linear Linear magnetic actuators include LinearMagnetic actuators Requires unusual semiconductor IJ12 Magnetic theLinear Induction Actuator (LIA), can be constructed with materials suchas soft magnetic alloys Actuator Linear Permanent Magnet high thrust,long travel, and (e.g. CoNiFe [1]) Synchronous Actuator (LPMSA), highefficiency using planar Some varieties also require permanent LinearReluctance Synchronous semiconductor fabrication magnetic materials suchas Actuator (LRSA), Linear Switched techniques Neodymium iron boron(NdFeB) Reluctance Actuator (LSRA), and Long actuator travel is Requirescomplex multi-phase drive the Linear Stepper Actuator (LSA). availablecircuitry Medium force is available High current operation Low voltageoperation

Description Advantages Disadvantages Examples BASIC OPERATION MODEOperational mode Actuator This is the simplest mode of Simple operationDrop repetition rate is usually limited Thermal inkjet directlyoperation: the actuator directly No external fields required to lessthan 10 KHz. However, this is Piezoelectric inkjet pushes ink suppliessufficient kinetic energy to Satellite drops can be not fundamental tothe method, but is IJ01, IJ02, IJ03, IJ04 expel the drop. The drop musthave a avoided if drop velocity is related to the refill method normallyIJ05, IJ06, IJ07, IJ09 sufficient velocity to overcome the less than 4m/s used IJ11, IJ12, IJ14, IJ16 surface tension. Can be efficient,depending All of the drop kinetic energy must be IJ20, 1322, IJ23, IJ24upon the actuator used provided by the actuator IJ25, IJ26, IJ27, IJ28Satellite drops usually form if drop velocity is greater than 4.5 m/sIJ29, IJ30, IJ31, IJ32 IJ33, IJ34, IJ35, IJ36 IJ37, IJ38, IJ39, IJ40IJ41, IJ42, IJ43, IJ44 Proximity The drops to be printed are selectedVery simple print head Requires close proximity between the Silverbrook,EP 0771 by some manner (e.g. thermally fabrication can be used printhead and the print media or 658 A2 and related induced surface tensionreduction of The drop selection means transfer roller patentapplications pressurized ink). Selected drops are does not need toprovide the May require two print heads printing separated from the inkin the nozzle energy required to separate alternate rows of the image bycontact with the print medium or the drop from the nozzle Monolithiccolor print heads are a transfer roller. difficult Electrostatic Thedrops to be printed are selected Very simple print head Requires veryhigh electrostatic field Silverbrook, EP 077 pull on ink by some manner(e.g. thermally fabrication can be used Electrostatic field for smallnozzle 658 A2 and related induced surface tension reduction of The dropselection means sizes is above air breakdown patent applicationspressurized ink). Selected drops are does not need to provide theElectrostatic field may attract dust Tone-Jet separated from the ink inthe nozzle energy required to separate by a strong electric field. thedrop from the nozzle Magnetic pull The drops to be printed are selectedVery simple print head Requires magnetic ink Silverbrook, EP 0771 on inkby some manner (e.g. thermally fabrication can be used Ink colors otherthan black are difficult 658 A2 and related induced surface tensionreduction of The drop selection means Requires very high magnetic fieldspatent applications pressurized ink). Selected drops are does not needto provide the separated from the ink in the nozzle energy required toseparate by a strong magnetic field acting on the drop from the nozzlethe magnetic ink. Shutter The actuator moves a shutter to High speed(>50 KHz) Moving parts are required IJ13, IJ17, IJ21 block ink flow tothe nozzle. The ink operation can be achieved Requires ink pressuremodulator pressure is pulsed at a multiple of the due to reduced refilltime Friction and wear must be considered drop ejection frequency. Droptiming can be very Stiction is possible accurate The actuator energy canbe very low Shuttered grill The actuator moves a shutter to Actuatorswith small travel Moving parts are required IJ08, IJ5, IJ18, IJ9 blockink flow through a grill to the can be used Requires ink pressuremodulator nozzle. The shutter movement need Actuators with small forceFriction and wear must be considered only be equal to the width of thegrill can be used Stiction is possible holes. High speed (>50 KHz)operation can be achieved Pulsed A pulsed magnetic field attracts anExtremely low energy Requires an external pulsed magnetic IJ10 magneticpull ‘ink pusher’ at the drop ejection operation is possible field onink pusher frequency. An actuator controls a No heat dissipationRequires special materials for both the catch, which prevents the inkpusher problems actuator and the ink pusher from moving when a drop isnot to Complex construction be ejected. AUXILIARY MECHANISM (APPLIED TOALL NOZZLES) Auxiliary Mechanism None The actuator directly fires theink Simplicity of construction Drop ejection energy must be suppliedMost inkjets, drop, and there is no external field or Simplicity ofoperation by individual nozzle actuator including other mechanismrequired. Small physical size piezoelectric and thermal bubble.IJ01-IJ07, IJ09, IJ11 IJ12, IJ14, IJ20, IJ22 IJ23-IJ45 Oscillating inkThe ink pressure oscillates, Oscillating ink pressure can Requiresexternal ink pressure Silverbrook, EP 0771 pressure providing much ofthe drop ejection provide a refill pulse, oscillator 658 A2 and related(including energy. The actuator selects which allowing higher operatingInk pressure phase and amplitude must patent applications acoustic dropsare to be fired by selectively speed be carefully controlled IJ08, IJ13,IJ15, IJ17 stimulation) blocking or enabling nozzles. The The actuatorsmay operate Acoustic reflections in the ink chamber IJ18, IJ19, IJ21 inkpressure oscillation may be with much lower energy must be designed forachieved by vibrating the print head, Acoustic lenses can be used orpreferably by an actuator in the to focus the sound on the ink supply.nozzles Media The print head is placed in close Low power Precisionassembly required Silverbrook, EP 077 1 proximity proximity to the printmedium. High accuracy Paper fibers may cause problems 658 A2 and relatedSelected drops protrude from the Simple print head Cannot print on roughsubstrates patent applications print head further than unselectedconstruction drops, and contact the print medium. The drop soaks intothe medium fast enough to cause drop separation. Transfer roller Dropsare printed to a transfer roller High accuracy Bulky Silverbrook, EP0771 instead of straight to the print Wide range of print Expensive 658A2 and related medium. A transfer roller can also be substrates can beused Complex construction patent applications used for proximity dropseparation. Ink can be dried on the Tektronix hot melt transfer rollerpiezoelectric inkjet Any of the IJ series Electrostatic An electricfield is used to accelerate Low power Field strength required forseparation Silverbrook, EP 0771 selected drops towards the print Simpleprint head of small drops is near or above air 658 A2 and relatedmedium. construction breakdown patent applications Tone-Jet Direct Amagnetic field is used to accelerate Low power Requires magnetic inkSilverbrook, EP 0771 magnetic field selected drops of magnetic inkSimple print head Requires strong magnetic field 658 A2 and relatedtowards the print medium. construction patent applications Cross Theprint head is placed in a constant Does not require magnetic Requiresexternal magnet IJ06, IJ16 magnetic field magnetic field. The Lorenzforce in a materials to be integrated in Current densities may be high,current carrying wire is used to move the print head resulting inelectromigration problems the actuator. manufacturing process Pulsed Apulsed magnetic field is used to Very low power operation Complex printhead construction IJ10 magnetic field cyclically attract a paddle, whichis possible Magnetic materials required in print pushes on the ink. Asmall actuator Small print head size head moves a catch, whichselectively prevents the paddle from moving. ACTUATOR AMPLIFICATION ORMODIFICATION METHOD Actuator amplification None No actuator mechanicalOperational simplicity Many actuator mechanisms have Thermal Bubbleamplification is used. The actuator insufficient travel, or insufficientforce, Inkjet directly drives the drop ejection to efficiently drive thedrop ejection IJ01, IJ02, IJ06, IJ07 process. process IJ16, IJ25, IJ26Differential An actuator material expands more Provides greater travelin a High stresses are involved Piezoelectric expansion on one side thanon the other. The reduced print head area Care must be taken that thematerials IJ03, IJ09, IJ17-IJ24 bend actuator expansion may be thermal,The bend actuator converts do not delaminate IJ27, IJ29-IJ39, IJ42,piezoelectric, magnetostrictive, or a high force low travel Residualbend resulting from high IJ43, IJ44 other mechanism. actuator mechanismto high temperature or high stress during travel, lower force formationmechanism. Transient bend A trilayer bend actuator where the Very goodtemperature High stresses are involved IJ40, IJ41 actuator two outsidelayers are identical. This stability Care must be taken that thematerials cancels bend due to ambient High speed, as a new drop do notdelaminate temperature and residual stress. The can be fired before heatactuator only responds to transient dissipates heating of one side orthe other. Cancels residual stress of formation Actuator stack A seriesof thin actuators are stacked. Increased travel Increased fabricationcomplexity Some piezoelectric This can be appropriate where Reduceddrive voltage Increased possibility of short circuits ink jets actuatorsrequire high electric field due to pinholes IJ04 strength, such aselectrostatic and piezoelectric actuators. Multiple Multiple smalleractuators are used Increases the force available Actuator forces may notadd linearly, IJ12, IJ13, IJ18, IJ20 actuators simultaneously to movethe ink. from an actuator reducing efficiency IJ22, IJ28, IJ42, IJ43Each actuator need provide only a Multiple actuators can be portion ofthe force required. positioned to control ink flow accurately LinearSpring A linear spring is used to transform a Matches low travelactuator Requires print head area for the spring IJ15 motion with smalltravel and high with higher travel force into a longer travel, lowerforce requirements motion. Non-contact method of motion transformationReverse spring The actuator loads a spring. When Better coupling to theink Fabrication complexity IJ05, IJ11 the actuator is turned off, thespring High stress in the spring releases. This can reverse theforce/distance curve of the actuator to make it compatible with theforce/time requirements of the drop ejection. Coiled A bend actuator iscoiled to provide Increases travel Generally restricted to planar IJ17,IJ21, IJ34, IJ35 actuator greater travel in a reduced chip area. Reduceschip area implementations due to extreme Planar implementations arefabrication difficulty in other relatively easy to fabricate.orientations. Flexure bend A bend actuator has a small region Simplemeans of increasing Care must be taken not to exceed the IJ10, IJ19,IJ33 actuator near the fixture point, which flexes travel of a bendactuator elastic limit in the flexure area much more readily than theStress distribution is very uneven remainder of the actuator. TheDifficult to accurately model with actuator flexing is effectivelyfinite element analysis converted from an even coiling to an angularbend, resulting in greater travel of the actuator tip. Gears Gears canbe used to increase travel Low force, low travel Moving parts arerequired IJ13 at the expense of duration. Circular actuators can be usedSeveral actuator cycles are required gears, rack and pinion, ratchets,and Can be fabricated using More complex drive electronics other gearingmethods can be used. standard surface MEMS Complex constructionprocesses Friction, friction, and wear are possible Catch The actuatorcontrols a small catch. Very low actuator energy Complex constructionIJ10 The catch either enables or disables Very small actuator sizeRequires external force movement of an ink pusher that is Unsuitable forpigmented inks controlled in a bulk manner. Buckle plate A buckle platecan be used to change Very fast movement Must stay within elastic limitsof the S. Hirata et al, “An a slow actuator into a fast motion. Itachievable materials for long device life Inkjet Head ..”, can alsoconvert a high force, low High stresses involved Proc. IEEE MEMS, travelactuator into a high travel, Generally high power requirement Feb. 1996,pp 418- medium force motion. 423. IJ18, IJ27 Tapered A tapered magneticpole can increase Linearizes the magnetic Complex construction IJ14magnetic pole travel at the expense of force. force/distance curve LeverA lever and fulcrum is used to Matches low travel actuator High stressaround the fulcrum IJ32, IJ36, IJ37 transform a motion with small travelwith higher travel and high force into a motion with requirements longertravel and lower force. The Fulcrum area has no linear lever can alsoreverse the direction of movement, and can be used travel. for a fluidseal Rotary The actuator is connected to a rotary High mechanicaladvantage Complex construction IJ28 impeller impeller. A small angulardeflection The ratio of force to travel Unsuitable for pigmented inks ofthe actuator results in a rotation of of the actuator can be theimpeller vanes, which push the matched to the nozzle ink againststationary vanes and out requirements by varying the of the nozzle.number of impeller vanes Acoustic lens A refractive or diffractive (e.g.zone No moving parts Large area required 1993 Hadimioglu et plate)acoustic lens is used to Only relevant for acoustic inkjets al, EUP550,192 concentrate sound waves. 1993 Elrod et al, EUP 572,220 Sharp Asharp point is used to concentrate Simple construction Difficult tofabricate using standard Tone-jet conductive an electrostatic field.VLSI processes for a surface ejecting point inkjet Only relevant forelectrostatic ink jets

ACTUATOR MOTION Actuator motion Description Advantages DisadvantagesExamples Volume The volume of the actuator changes, Simple constructionin the High energy is typically required Hewlett-Packard expansionpushing the ink in all directions. case of thermal ink jet to achievevolume expansion. This Thermal Inkjet leads to thermal stress,cavitation, Canon Bubblejet and kogation in thermal ink jetimplementations Linear, normal The actuator moves in a directionEfficient coupling to ink High fabrication complexity may IJ01, IJ02,IJ04, IJ07 to chip surface normal to the print head surface. The dropsejected normal to the be required to achieve perpendicular IJ11, IJ14nozzle is typically in the line of surface motion movement. Linear,parallel The actuator moves parallel to the Suitable for planarFabrication complexity IJ12, IJ13, IJ15, IJ33, to chip surface printhead surface. Drop ejection fabrication Friction IJ34, IJ35, IJ36 maystill be normal to the surface. Stiction Membrane An actuator with ahigh force but The effective area of the Fabrication complexity 1982Howkins push small area is used to push a stiff actuator becomes theActuator size U.S. Pat. No. 4,459,601 membrane that is in contact withthe membrane area Difficulty of integration in a VLSI ink. processRotary The actuator causes the rotation of Rotary levers may be usedDevice complexity IJ05, IJ08, IJ13, IJ28 some element, such a grill orto increase travel May have friction at a pivot point impeller Smallchip area requirements Bend The actuator bends when energized. A verysmall change in Requires the actuator to be made 1970 Kyser et al Thismay be due to differential dimensions can be from at least two distinctlayers, or U.S. Pat. No. 3,946,398 thermal expansion, piezoelectricconverted to a large motion. to have a thermal difference across 1973Stemme expansion, magnetostriction, or other the actuator U.S. Pat. No.3,747,120 form of relative dimensional change. IJ03, IJ09, IJ10, IJ19IJ23, IJ24, IJ25, IJ29 IJ30, IJ31, IJ33, IJ34 IJ35 Swivel The actuatorswivels around a central Allows operation where the Inefficient couplingto the ink IJ06 pivot. This motion is suitable where net linear force onthe motion there are opposite forces applied to paddle is zero oppositesides of the paddle, e.g. Small chip area Lorenz force. requirementsStraighten The actuator is normally bent, and Can be used with shapeRequires careful balance of IJ26, IJ32 straightens when energized.memory alloys where the stresses to ensure that the quiescent austenicphase is planar bend is accurate Double bend The actuator bends in onedirection One actuator can be used to Difficult to make the dropsejected IJ36, IJ37, IJ38 when one element is energized, and power twonozzles. by both bend directions identical. bends the other way whenanother Reduced chip size. A small efficiency loss compared element isenergized. Not sensitive to ambient to equivalent single bend actuators.temperature Shear Energizing the actuator causes a Can increase theeffective Not readily applicable to other 1985 Fishbeck shear motion inthe actuator material. travel of piezoelectric actuator mechanisms U.S.Pat. No. 4,584,590 actuators Radial The actuator squeezes an inkRelatively easy to fabricate High force required 1970 Zoltanconstriction reservoir, forcing ink from a single nozzles from glassInefficient U.S. Pat. No. 3,683,212 constricted nozzle. tubing asmacroscopic Difficult to integrate with VLSI structures processesCoil/uncoil A coiled actuator uncoils or coils Easy to fabricate as aDifficult to fabricate for non- IJ17, IJ21, IJ34, IJ35 more tightly. Themotion of the free planar VLSI process planar devices end of theactuator ejects the ink. Small area required, Poor out-of-planestiffness therefore low cost Bow The actuator bows (or buckles) in theCan increase the speed of Maximum travel is constrained IJ16, IJ18, IJ27middle when energized. travel High force required Mechanically rigidPush-Pull Two actuators control a shutter. One The structure is pinnedat Not readily suitable for inkjets IJ18 actuator pulls the shutter, andthe both ends, so has a high which directly push the ink other pushesit. out-of-plane rigidity Curl inwards A set of actuators curl inwardsto Good fluid flow to the Design complexity IJ20, IJ42 reduce the volumeof ink that they region behind the actuator enclose. increasesefficiency Curl outwards A set of actuators curl outwards, Relativelysimple Relatively large chip area IJ43 pressurizing ink in a chamberconstruction surrounding the actuators, and expelling ink from a nozzlein the chamber. Iris Multiple vanes enclose a volume of High efficiencyHigh fabrication complexity IJ22 ink. These simultaneously rotate, Smallchip area Not suitable for pigmented inks reducing the volume betweenthe vanes. Acoustic The actuator vibrates at a high The actuator can beLarge area required for efficient 1993 Hadimioglu et vibrationfrequency. physically distant from the operation at useful frequenciesal, EUP 550,192 ink Acoustic coupling and crosstalk 1993 Elrod et al,EUP Complex drive circuitry 572,220 Poor control of drop volume andposition None In various ink jet designs the actuator No moving partsVarious other tradeoffs are Silverbrook, EP 0771 does not move. requiredto eliminate moving parts 658 A2 and related patent applicationsTone-jet

NOZZLE REFILL METHOD Nozzle refill method Description AdvantagesDisadvantages Examples Surface After the actuator is energized, itFabrication simplicity Low speed Thermal inkjet tension typicallyreturns rapidly to its normal Operational simplicity Surface tensionforce relatively Piezoelectric inkjet position. This rapid return sucksin small compared to actuator force IJ01-IJ07, IJ10-IJ14 air through thenozzle opening. The Long refill time usually dominates IJ16, IJ20,IJ22-IJ45 ink surface tension at the nozzle then the total repetitionrate exerts a small force restoring the meniscus to a minimum area.Shuttered Ink to the nozzle chamber is High speed Requires common inkpressure IJ08, IJ13, IJ15, IJ17 oscillating ink provided at a pressurethat oscillates Low actuator energy, as the oscillator IJ18, IJ19, IJ21pressure at twice the drop ejection frequency. actuator need only openor May not be suitable for pigmented When a drop is to be ejected, theclose the shutter, instead of inks shutter is opened for 3 half cycles:ejecting the ink drop drop ejection, actuator return, and refill. Refillactuator After the main actuator has ejected a High speed, as the nozzleis Requires two independent IJ09 drop a second (refill) actuator isactively refilled actuators per nozzle energized. The refill actuatorpushes ink into the nozzle chamber. The refill actuator returns slowly,to prevent its return from emptying the chamber again. Positive ink Theink is held a slight positive High refill rate, therefore a Surfacespill must be prevented Silverbrook, EP 0771 pressure pressure. Afterthe ink drop is high drop repetition rate is Highly hydrophobic printhead 658 A2 and related ejected, the nozzle chamber fills possiblesurfaces are required patent applications quickly as surface tension andink Alternative for: pressure both operate to refill the IJ01-IJ07,IJ10-IJ14 nozzle. IJ16, IJ20, IJ22-IJ45

METHOD OF RESTRICTING BACK-FLOW THROUGH INLET Inlet back-flowrestriction method Description Advantages Disadvantages Examples Longinlet The ink inlet channel to the nozzle Design simplicity Restrictsrefill rate Thermal ink jet channel chamber is made long and relativelyOperational simplicity May result in a relatively large Piezoelectricink jet narrow, relying on viscous drag to Reduces crosstalk chip areaIJ42, IJ43 reduce inlet back-flow. Only partially effective Positive inkThe ink is under a positive pressure, Drop selection and Requires amethod (such as a Silverbrook, EP 0771 pressure so that in the quiescentstate some of separation forces can be nozzle rim or effective hydro-658 A2 and related the ink drop already protrudes from reducedphobizing, or both) to prevent flood- patent applications the nozzle.Fast refill time ing of the ejection surface of the print Possibleoperation of This reduces the pressure in the head. the following:nozzle chamber which is required to IJ01-IJ07, IJ09-IJ12 eject a certainvolume of ink. The IJ14, IJ16, IJ20, IJ22, reduction in chamber pressureresults IJ23-IJ34, IJ36-IJ41 in a reduction in ink pushed out IJ44through the inlet. Baffle One or more baffles are placed in the Therefill rate is not as Design complexity HP Thermal Ink Jet inlet inkflow. When the actuator is restricted as the long inlet May increasefabrication Tektronix energized, the rapid ink movement method.complexity (e.g. Tektronix hot melt piezoelectric ink jet creates eddieswhich restrict the flow Reduces crosstalk Piezoelectric print heads).through the inlet. The slower refill process is unrestricted, and doesnot result in eddies. Flexible flap In this method recently disclosed bySignificantly reduces back- Not applicable to most inkjet Canonrestricts inlet Canon, the expanding actuator flow for edge-shooterconfigurations (bubble) pushes on a flexible flap thermal ink jetdevices Increased fabrication complexity that restricts the inlet.Inelastic deformation of polymer flap results in creep over extended useInlet filter A filter is located between the ink Additional advantage ofink Restricts refill rate IJ04, IJ12, IJ24, IJ27 inlet and the nozzlechamber. The filtration May result in complex IJ29, IJ30 filter has amultitude of small holes Ink filter may be fabricated construction orslots, restricting ink flow. The with no additional process filter alsoremoves particles which steps may block the nozzle. Small inlet The inkinlet channel to the nozzle Design simplicity Restricts refill rateIJ02, IJ37, IJ44 compared to chamber has a substantially smaller Mayresult in a relatively large nozzle cross section than that of thenozzle, chip area resulting in easier ink egress out of Only partiallyeffective the nozzle than out of the inlet. Inlet shutter A secondaryactuator controls the Increases speed of the ink- Requires separaterefill actuator IJ09 position of a shutter, closing off the jet printhead operation and drive circuit ink inlet when the main actuator isenergized. The inlet is The method avoids the problem of Back-flowproblem is Requires careful design to IJ01, IJ03, IJ05, IJ06 locatedbehind inlet back-flow by arranging the ink- eliminated minimize thenegative pressure be- IJ07, IJ10, IJ11, IJ14 the ink- pushing surface ofthe actuator hind the paddle IJ16, IJ22, IJ23, IJ25 pushing between theinlet and the nozzle. IJ28, IJ31, IJ32, IJ33 surface IJ34, IJ35, IJ36,IJ39 IJ40, IJ41 Part of the The actuator and a wall of the inkSignificant reductions in Small increase in fabrication IJ07, IJ20,IJ26, IJ38 actuator chamber are arranged so that the back-flow can beachieved complexity moves to shut motion of the actuator closes off theCompact designs possible off the inlet inlet. Nozzle In someconfigurations of ink jet, Ink back-flow problem is None related to inkback-flow on Silverbrook, EP 0771 actuator does there is no expansion ormovement eliminated actuation 658 A2 and related not result in of anactuator which may cause ink patent applications ink back-flow back-flowthrough the inlet. Valve-jet Tone-jet IJ08, IJ13, IJ15, IJ17 IJ18, IJ19,IJ21

NOZZLE CLEARING METHOD Nozzle Clearing method Description AdvantagesDisadvantages Examples Normal nozzle All of the nozzles are fired Noadded complexity on May not be sufficient to displace Most ink jetsystems firing periodically, before the ink has a the print head driedink IJ01-IJ07, IJ09-IJ12 chance to dry. When not in use the IJ14, IJ16,IJ20, IJ22 nozzles are sealed (capped) against IJ23-IJ34, IJ36-IJ45 air.The nozzle firing is usually performed during a special clearing cycle,after first moving the print head to a cleaning station. Extra power toIn systems which heat the ink, but do Can be highly effective ifRequires higher drive voltage for Silverbrook, EP 0771 ink heater notboil it under normal situations, the heater is adjacent to the clearing658 A2 and related nozzle clearing can be achieved by nozzle May requirelarger drive transistors patent applications over-powering the heaterand boiling ink at the nozzle. Rapid The actuator is fired in rapid Doesnot require extra Effectiveness depends substantially May be used with:succession of succession. In some configurations, drive circuits on theprint head upon the configuration of the inkjet IJ01-IJ07, IJ09-IJ11actuator this may cause heat build-up at the Can be readily controllednozzle IJ14, IJ16, IJ20, IJ22 pulses nozzle which boils the ink,clearing and initiated by digital logic IJ23-IJ25, IJ27-IJ34 the nozzle.In other situations, it may IJ36-IJ45 cause sufficient vibrations todislodge clogged nozzles. Extra power to Where an actuator is notnormally A simple solution where Not suitable where there is a hard Maybe used with: ink pushing driven to the limit of its motion, applicablelimit to actuator movement IJ03, IJ09, IJ16, IJ20 actuator nozzleclearing may be assisted by IJ23, IJ24, IJ25, IJ27 providing an enhanceddrive signal IJ29, IJ30, IJ31, IJ32 to the actuator. IJ39, IJ40, IJ41,IJ42 IJ43, IJ44, IJ45 Acoustic An ultrasonic wave is applied to the Ahigh nozzle clearing High implementation cost if IJ08, IJ13, IJ15, IJ17resonance ink chamber. This wave is of an capability can be achievedsystem does not already include an IJ18, IJ19, IJ21 appropriateamplitude and frequency May be implemented at acoustic actuator to causesufficient force at the nozzle very low cost in systems to clearblockages. This is easiest to which already include achieve if theultrasonic wave is at a acoustic actuators resonant frequency of the inkcavity. Nozzle A microfabricated plate is pushed Can clear severelyclogged Accurate mechanical alignment is Silverbrook, EP 0771 clearingplate against the nozzles. The plate has a nozzles required 658 A2 andrelated post for every nozzle. The array of Moving parts are requiredpatent applications posts There is risk of damage to the nozzlesAccurate fabrication is required Ink pressure The pressure of the ink isMay be effective where Requires pressure pump or other May be used withall pulse temporarily increased so that ink other methods cannot bepressure actuator IJ series ink jets streams from all of the nozzles.This used Expensive may be used in conjunction with Wasteful of inkactuator energizing. Print head A flexible ‘blade’ is wiped across theEffective for planar print Difficult to use if print head sur- Many inkjet systems wiper print head surface. The blade is head surfaces face isnon-planar or very fragile usually fabricated from a flexible Low costRequires mechanical parts polymer, e.g. rubber or synthetic Blade canwear out in high volume elastomer. print systems Separate ink A separateheater is provided at the Can be effective where Fabrication complexityCan be used with boiling heater nozzle although the normal drop e- othernozzle clearing many IJ series ink ection mechanism does not require it.methods cannot be used jets The heaters do not require individual Can beimplemented at no drive circuits, as many nozzles can additional cost insome be cleared simultaneously, and no inkjet configurations imaging isrequired.

NOZZLE PLATE CONSTRUCTION Nozzle plate construction DescriptionAdvantages Disadvantages Examples Electroformed A nozzle plate isseparately Fabrication simplicity High temperatures and pressuresHewlett Packard nickel fabricated from electroformed nickel, arerequired to bond nozzle plate Thermal Inkjet and bonded to the printhead chip. Minimum thickness constraints Differential thermal expansionLaser ablated Individual nozzle holes are ablated No masks required Eachhole must be individually Canon Bubblejet or drilled by an intense UVlaser in a nozzle Can be quite fast formed 1988 Sercel et al., polymerplate, which is typically a polymer Some control over nozzle Specialequipment required SPIE, Vol. 998 such as polyimide or polysulphoneprofile is possible Slow where there are many Excimer Beam Equipmentrequired is thousands of nozzles per print head Applications, pp. 76-83relatively low cost May produce thin burrs at exit 1993 Watanabe et al.,holes U.S. Pat. No. 5,208,604 Silicon micro- A separate nozzle plate isHigh accuracy is attainable Two part construction K. Bean, IEEE machinedmicromachined from single crystal High cost Transactions on silicon, andbonded to the print head Requires precision alignment Electron Devices,wafer. Nozzles may be clogged by Vol. ED-25, No. 10, adhesive 1978, pp1185-1195 Xerox 1990 Hawkins et al., U.S. Pat. No. 4,899,181 Glass Fineglass capillaries are drawn from No expensive equipment Very smallnozzle sizes are 1970 Zoltan capillaries glass tubing. This method hasbeen required difficult to form U.S. Pat. No. 3,683,212 used for makingindividual nozzles, Simple to make single Not suited for mass productionbut is difficult to use for bulk nozzles manufacturing of print headswith thousands of nozzles. Monolithic, The nozzle plate is deposited asa High accuracy (<1 μm) Requires sacrificial layer under theSilverbrook, EP 0771 surface micro- layer using standard VLSI depositionMonolithic nozzle plate to form the nozzle 658 A2 and related machinedtechniques. Nozzles are etched in the Low cost chamber patentapplications using VLSI nozzle plate using VLSI lithography Existingprocesses can be Surface may be fragile to the touch IJ01, IJ02, IJ04,IJ11 lithographic and etching. used IJ12, IJ17, IJ18, IJ20 processesIJ22, IJ24, IJ27, IJ28 IJ29, IJ30, IJ31, IJ32 IJ33, IJ34, IJ36, IJ37IJ38, IJ39, IJ40, IJ41 IJ42, IJ43, IJ44 Monolithic, The nozzle plate isa buried etch stop High accuracy (<1 μm) Requires long etch times IJ03,IJ05, IJ06, IJ07 etched in the wafer. Nozzle chambers are MonolithicRequires a support wafer IJ08, IJ09, IJ10, IJ13 through etched in thefront of the wafer, and Low cost IJ14, IJ15, IJ16, IJ19 substrate thewafer is thinned from the back No differential expansion IJ21, IJ23,IJ25, IJ26 side. Nozzles are then etched in the etch stop layer. Nonozzle Various methods have been tried to No nozzles to become Difficultto control drop position Ricoh 1995 Sekiya plate eliminate the nozzlesentirely, to clogged accurately et al prevent nozzle clogging. TheseCrosstalk problems U.S. Pat. No. 5,412,413 include thermal bubblemechanisms 1993 Hadimioglu et and acoustic lens mechanisms al EUP550,192 1993 Elrod et al EUP 572,220 Trough Each drop ejector has atrough Reduced manufacturing Drop firing direction is sensitive to IJ35through which a paddle moves. complexity wicking. There is no nozzleplate. Monolithic Nozzle slit The elimination of nozzle holes and Nonozzles to become Difficult to control drop position 1989 Saito et alinstead of replacement by a slit encompassing clogged accurately U.S.Pat. No. 4,799,068 individual many actuator positions reduces Crosstalkproblems nozzles nozzle clogging, but increases crosstalk due to inksurface waves

DROP EJECTION DIRECTION Ejection direction Description AdvantagesDisadvantages Examples Edge Ink flow is along the surface of the Simpleconstruction Nozzles limited to edge Canon Bubblejet (‘edge chip, andink drops are ejected from No silicon etching required High resolutionis difficult 1979 Endo et al GB shooter’) the chip edge. Good heatsinking via Fast color printing requires one patent 2,007,162 substrateprint head per color Xerox heater-in-pit Mechanically strong 1990Hawkins et al Ease of chip handing U.S. Pat. No. 4,899,181 Tone-jetSurface Ink flow is along the surface of the No bulk silicon etchingMaximum ink flow is severely Hewlett-Packard TIJ (‘roof shooter’) chip,and ink drops are ejected from required restricted 1982 Vaught et al thechip surface, normal to the plane Silicon can make an U.S. Pat. No.4,490,728 of the chip. effective heat sink IJ02, IJ11, IJ12, IJ20Mechanical strength IJ22 Through chip, Ink flow is through the chip, andink High ink flow Requires bulk silicon etching Silverbrook, EP 0771forward drops are ejected from the front Suitable for pagewidth 658 A2and related (‘up shooter’) surface of the chip. print patentapplications High nozzle packing IJ04, IJ17, IJ18, IJ24 densitytherefore low IJ27-IJ45 manufacturing cost Through chip, Ink flow isthrough the chip, and ink High ink flow Requires wafer thinning IJ01,IJ03, IJ05, IJ06 reverse drops are ejected from the rear Suitable forpagewidth Requires special handling during IJ07, IJ08, IJ09, IJ10 (‘downsurface of the chip. print manufacture IJ13, IJ14, IJ15, IJ16 shooter’)High nozzle packing IJ19, IJ21, IJ23, IJ25 density therefore low IJ26manufacturing cost Through Ink flow is through the actuator, Suitablefor piezoelectric Pagewidth print heads require Epson Stylus actuatorwhich is not fabricated as part of the print heads several thousandconnections to drive Tektronix hot melt same substrate as the drivecircuits piezoelectric ink jets transistors. Cannot be manufactured instandard CMOS fabs Complex assembly required

INK TYPE Ink type Description Advantages Disadvantages Examples Aqueous,dye Water based ink which typically Environmentally friendly Slow dryingMost existing inkjets contains: water, dye, surfactant, No odorCorrosive All IJ series ink jets humectant, and biocide. Bleeds on paperSilverbrook, EP 0771 Modern ink dyes have high water- May strikethrough658 A2 and related fastness, light fastness Cockles paper patentapplications Aqueous, Water based ink which typically Environmentallyfriendly Slow drying IJ02, 1J04, IJ21, IJ26 pigment contains: water,pigment, surfactant, No odor Corrosive IJ27, IJ30 humectant, andbiocide. Reduced bleed Pigment may clog nozzles Silverbrook, EP 0771Pigments have an advantage in Reduced wicking Pigment may clog actuator658 A2 and related reduced bleed, wicking and Reduced strikethroughmechanisms patent applications strikethrough. Cockles paperPiezoelectric ink-jets Thermal ink jets (with significant restrictions)Methyl Ethyl MEK is a highly volatile solvent Very fast drying OdorousAll IJ series ink jets Ketone (MEK) used for industrial printing onPrints on various substrates Flammable difficult surfaces such asaluminum such as metals and plastics cans. Alcohol Alcohol based inkscan be used Fast drying Slight odor All IJ series ink jets (ethanol, 2-where the printer must operate at Operates at sub-freezing Flammablebutanol, and temperatures below the freezing temperatures others) pointof water. An example of this is Reduced paper cockle in-camera consumerphotographic Low cost printing. Phase change The ink is solid at roomtemperature, No drying time- ink High viscosity Tektronix hot melt (hotmelt) and is melted in the print head before instantly freezes on thePrinted ink typically has a ‘waxy’ piezoelectric ink jets jetting. Hotmelt inks are usually print medium feel 1989 Nowak wax based, with amelting point Almost any print medium Printed pages may ‘block’ U.S.Pat. No. 4,820,346 around 80° C. After jetting the ink can be used Inktemperature may be above the All IJ series ink jets freezes almostinstantly upon No paper cockle occurs curie point of permanent magnetscontacting the print medium or a No wicking occurs Ink heaters consumepower transfer roller. No bleed occurs Long warm-up time Nostrikethrough occurs Oil Oil based inks are extensively used Highsolubility medium for High viscosity: this is a significant All IJseries ink jets in offset printing. They have some dyes limitation foruse in inkjets, which advantages in improved Does not cockle paperusually require a low viscosity. Some characteristics on paper(especially Does not wick through short chain and multi-branched oils nowicking or cockle). Oil soluble paper have a sufficiently low viscosity.dies and pigments are required. Slow drying Microemulsion Amicroemulsion is a stable, self Stops ink bleed Viscosity higher thanwater All IJ series ink jets forming emulsion of oil, water, and Highdye solubility Cost is slightly higher than water surfactant. Thecharacteristic drop Water, oil, and amphiphilic based ink size is lessthan 100 nm, and is soluble dies can be used High surfactantconcentration determined by the preferred Can stabilize pigment required(around 5%) curvature of the surfactant. suspensions

Ink Jet Printing

A large number of new forms of ink jet printers have been developed tofacilitate alternative ink jet technologies for the image processing anddata distribution system. Various combinations of ink jet devices can beincluded in printer devices incorporated as part of the presentinvention. Australian Provisional Patent Applications relating to theseink jets which are specifically incorporated by cross reference include:

Australian Provisional Number Filing Date Title PO8066 15-Jul-97 ImageCreation Method and Apparatus (IJ01) PO8072 15-Jul-97 Image CreationMethod and Apparatus (IJ02) PO8040 15-Jul-97 Image Creation Method andApparatus (IJ03) PO8071 15-Jul-97 Image Creation Method and Apparatus(IJ04) PO8047 15-Jul-97 Image Creation Method and Apparatus (IJ05)PO8035 15-Jul-97 Image Creation Method and Apparatus (IJ06) PO804415-Jul-97 Image Creation Method and Apparatus (IJ07) PO8063 15-Jul-97Image Creation Method and Apparatus (IJ08) PO8057 15-Jul-97 ImageCreation Method and Apparatus (IJ09) PO8056 15-Jul-97 Image CreationMethod and Apparatus (IJ10) PO8069 15-Jul-97 Image Creation Method andApparatus (IJ11) PO8049 15-Jul-97 Image Creation Method and Apparatus(IJ12) PO8036 15-Jul-97 Image Creation Method and Apparatus (IJ13)PO8048 15-Jul-97 Image Creation Method and Apparatus (IJ14) PO807015-Jul-97 Image Creation Method and Apparatus (IJ15) PO8067 15-Jul-97Image Creation Method and Apparatus (IJ16) PO8001 15-Jul-97 ImageCreation Method and Apparatus (IJ17) PO8038 15-Jul-97 Image CreationMethod and Apparatus (IJ18) PO8033 15-Jul-97 Image Creation Method andApparatus (IJ19) PO8002 15-Jul-97 Image Creation Method and Apparatus(IJ20) PO8068 15-Jul-97 Image Creation Method and Apparatus (IJ21)PO8062 15-Jul-97 Image Creation Method and Apparatus (IJ22) PO803415-Jul-97 Image Creation Method and Apparatus (IJ23) PO8039 15-Jul-97Image Creation Method and Apparatus (IJ24) PO8041 15-Jul-97 ImageCreation Method and Apparatus (IJ25) PO8004 15-Jul-97 Image CreationMethod and Apparatus (IJ26) PO8037 15-Jul-97 Image Creation Method andApparatus (IJ27) PO8043 15-Jul-97 Image Creation Method and Apparatus(IJ28) PO8042 15-Jul-97 Image Creation Method and Apparatus (IJ29)PO8064 15-Jul-97 Image Creation Method and Apparatus (IJ30) PO938923-Sep-97 Image Creation Method and Apparatus (IJ31) PO9391 23-Sep-97Image Creation Method and Apparatus (IJ32) PP0888 12-Dec-97 ImageCreation Method and Apparatus (IJ33) PP0891 12-Dec-97 Image CreationMethod and Apparatus (IJ34) PP0890 12-Dec-97 Image Creation Method andApparatus (IJ35) PP0873 12-Dec-97 Image Creation Method and Apparatus(IJ36) PP0993 12-Dec-97 Image Creation Method and Apparatus (IJ37)PP0890 12-Dec-97 Image Creation Method and Apparatus (IJ38) PP139819-Jan-98 An Image Creation Method and Apparatus (IJ39) PP2592 25-Mar-98An Image Creation Method and Apparatus (IJ40) PP2593 25-Mar-98 ImageCreation Method and Apparatus (IJ41) PP3991  9-Jun-98 Image CreationMethod and Apparatus (IJ42) PP3987  9-Jun-98 Image Creation Method andApparatus (IJ43) PP3985  9-Jun-98 Image Creation Method and Apparatus(IJ44) PP3983  9-Jun-98 Image Creation Method and Apparatus (IJ45)

Ink Jet Manufacturing

Further, the present application may utilize advanced semiconductorfabrication techniques in the construction of large arrays of ink jetprinters. Suitable manufacturing techniques are described in thefollowing Australian provisional patent specifications incorporated hereby cross-reference:

Australian Provisional Number Filing Date Title PO7935 15-Jul-97 AMethod of Manufacture of an Image Creation Apparatus (IJM01) PO793615-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM02)PO7937 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus(IJM03) PO8061 15-Jul-97 A Method of Manufacture of an Image CreationApparatus (IJM04) PO8054 15-Jul-97 A Method of Manufacture of an ImageCreation Apparatus (IJM05) PO8065 15-Jul-97 A Method of Manufacture ofan Image Creation Apparatus (IJM06) PO8055 15-Jul-97 A Method ofManufacture of an Image Creation Apparatus (IJM07) PO8053 15-Jul-97 AMethod of Manufacture of an Image Creation Apparatus (IJM08) PO807815-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM09)PO7933 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus(IJM10) PO7950 15-Jul-97 A Method of Manufacture of an Image CreationApparatus (IJM11) PO7949 15-Jul-97 A Method of Manufacture of an ImageCreation Apparatus (IJM12) PO8060 15-Jul-97 A Method of Manufacture ofan Image Creation Apparatus (IJM13) PO8059 15-Jul-97 A Method ofManufacture of an Image Creation Apparatus (IJM14) PO8073 15-Jul-97 AMethod of Manufacture of an Image Creation Apparatus (IJM15) PO807615-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM16)PO8075 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus(IJM17) PO8079 15-Jul-97 A Method of Manufacture of an Image CreationApparatus (IJM18) PO8050 15-Jul-97 A Method of Manufacture of an ImageCreation Apparatus (IJM19) PO8052 15-Jul-97 A Method of Manufacture ofan Image Creation Apparatus (IJM20) PO7948 15-Jul-97 A Method ofManufacture of an Image Creation Apparatus (IJM21) PO7951 15-Jul-97 AMethod of Manufacture of an Image Creation Apparatus (IJM22) PO807415-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM23)PO7941 15-Jul-97 A Method of Manufacture of an Image Creation Apparatus(IJM24) PO8077 15-Jul-97 A Method of Manufacture of an Image CreationApparatus (IJM25) PO8058 15-Jul-97 A Method of Manufacture of an ImageCreation Apparatus (IJM26) PO8051 15-Jul-97 A Method of Manufacture ofan Image Creation Apparatus (IJM27) PO8045 15-Jul-97 A Method ofManufacture of an Image Creation Apparatus (IJM28) PO7952 15-Jul-97 AMethod of Manufacture of an Image Creation Apparatus (IJM29) PO804615-Jul-97 A Method of Manufacture of an Image Creation Apparatus (IJM30)PO8503 11-Aug-97 A Method of Manufacture of an Image Creation Apparatus(IJM30a) PO9390 23-Sep-97 A Method of Manufacture of an Image CreationApparatus (IJM31) PO9392 23-Sep-97 A Method of Manufacture of an ImageCreation Apparatus (IJM32) PP0889 12-Dec-97 A Method of Manufacture ofan Image Creation Apparatus (IJM35) PP0887 12-Dec-97 A Method ofManufacture of an Image Creation Apparatus (IJM36) PP0882 12-Dec-97 AMethod of Manufacture of an Image Creation Apparatus (IJM37) PP087412-Dec-97 A Method of Manufacture of an Image Creation Apparatus (IJM38)PP1396 19-Jan-98 A Method of Manufacture of an Image Creation Apparatus(IJM39) PP2591 25-Mar-98 A Method of Manufacture of an Image CreationApparatus (IJM41) PP3989  9-Jun-98 A Method of Manufacture of an ImageCreation Apparatus (IJM40) PP3990  9-Jun-98 A Method of Manufacture ofan Image Creation Apparatus (IJM42) PP3986  9-Jun-98 A Method ofManufacture of an Image Creation Apparatus (IJM43) PP3984  9-Jun-98 AMethod of Manufacture of an Image Creation Apparatus (IJM44) PP3982 9-Jun-98 A Method of Manufacture of an Image Creation Apparatus (IJM45)

Fluid Supply

Further, the present application may utilize an ink delivery system tothe ink jet head. Delivery systems relating to the supply of ink to aseries of ink jet nozzles are described in the following Australianprovisional patent specifications, the disclosure of which are herebyincorporated by cross-reference:

Australian Provisional Number Filing Date Title PO8003 Jul-15-97 SupplyMethod and Apparatus (F1) PO8005 Jul-15-97 Supply Method and Apparatus(F2) PO9404 Sep-23-97 A Device and Method (F3)

MEMS Technology

Further, the present application may utilize advanced semiconductormicroelectromechanical techniques in the construction of large arrays ofink jet printers. Suitable microelectromechanical techniques aredescribed in the following Australian provisional patent specificationsincorporated here by cross-reference:

Australian Provisional Number Filing Date Title PO7943 Jul-15-97 Adevice (MEMS01) PO8006 Jul-15-97 A device (MEMS02) PO8007 Jul-15-97 Adevice (MEMS03) PO8008 Jul-15-97 A device (MEMS04) PO8010 Jul-15-97 Adevice (MEMS05) PO8011 Jul-15-97 A device (MEM506) PO7947 Jul-15-97 Adevice (MEMS07) PO7945 Jul-15-97 A device (MEMS08) PO7944 Jul-15-97 Adevice (MEMS09) PO7946 Jul-15-97 A device (MEMS10) PO9393 Sep-23-97 ADevice and Method (MEMS11) PP0875 Dec-12-97 A Device (MEMS12) PP0894Dec-12-97 A Device and Method (MEMS13)

IR Technologies

Further, the present application may include the utilization of adisposable camera system such as those described in the followingAustralian provisional patent specifications incorporated here bycross-reference:

Australian Provisional Number Filing Date Title PP0895 Dec-12-97 AnImage Creation Method and Apparatus (IR01) PP0870 Dec-12-97 A Device andMethod (IR02) PP0869 Dec-12-97 A Device and Method (IR04) PP0887Dec-12-97 Image Creation Method and Apparatus (IR05) PP0885 Dec-12-97 AnImage Production System (IR06) PP0884 Dec-12-97 Image Creation Methodand Apparatus (IR10) PP0886 Dec-12-97 Image Creation Method andApparatus (IR12) PP0871 Dec-12-97 A Device and Method (IR13) PP0876Dec-12-97 An Image Processing Method and Apparatus (IR14) PP0877Dec-12-97 A Device and Method (IR16) PP0878 Dec-12-97 A Device andMethod (IR17) PP0879 Dec-12-97 A Device and Method (IR18) PP0883Dec-12-97 A Device and Method (IR19) PP0880 Dec-12-97 A Device andMethod (IR20) PP0881 Dec-12-97 A Device and Method (IR21)

DotCard Technologies

Further, the present application may include the utilization of a datadistribution system such as that described in the following Australianprovisional patent specifications incorporated here by cross-reference:

Australian Provisional Number Filing Date Title PP2370 Mar-16-98 DataProcessing Method and Apparatus (Dot01) PP2371 Mar-16-98 Data ProcessingMethod and Apparatus (Dot02)

Artcam Technologies

Further, the present application may include the utilization of cameraand data processing techniques such as an Artcam type device asdescribed in the following Australian provisional patent specificationsincorporated here by cross-reference:

Australian Provisional Number Filing Date Title PO7991 Jul-15-97 ImageProcessing Method and Apparatus (ART01) PO8505 Aug-11-97 ImageProcessing Method and Apparatus (ART01a) PO7988 Jul-15-97 ImageProcessing Method and Apparatus (ART02) PO7993 Jul-15-97 ImageProcessing Method and Apparatus (ART03) PO8012 Jul-15-97 ImageProcessing Method and Apparatus (ART05) PO8017 Jul-15-97 ImageProcessing Method and Apparatus (ART06) PO8014 Jul-15-97 Media Device(ART07) PO8025 Jul-15-97 Image Processing Method and Apparatus (ART08)PO8032 Jul-15-97 Image Processing Method and Apparatus (ART09) PO7999Jul-15-97 Image Processing Method and Apparatus (ART10) PO7998 Jul-15-97Image Processing Method and Apparatus (ART11) PO8031 Jul-15-97 ImageProcessing Method and Apparatus (ART12) PO8030 Jul-15-97 Media Device(ART13) PO8498 Aug-11-97 Image Processing Method and Apparatus (ART14)PO7997 Jul-15-97 Media Device (ART15) PO7979 Jul-15-97 Media Device(ART16) PO8015 Jul-15-97 Media Device (ART17) PO7978 Jul-15-97 MediaDevice (ART18) PO7982 Jul-15-97 Data Processing Method and Apparatus(ART19) PO7989 Jul-15-97 Data Processing Method and Apparatus (ART20)PO8019 Jul-15-97 Media Processing Method and Apparatus (ART21) PO7980Jul-15-97 Image Processing Method and Apparatus (ART22) PO7942 Jul-15-97Image Processing Method and Apparatus (ART23) PO8018 Jul-15-97 ImageProcessing Method and Apparatus (ART24) PO7938 Jul-15-97 ImageProcessing Method and Apparatus (ART25) PO8016 Jul-15-97 ImageProcessing Method and Apparatus (ART26) PO8024 Jul-15-97 ImageProcessing Method and Apparatus (ART27) PO7940 Jul-15-97 Data ProcessingMethod and Apparatus (ART28) PO7939 Jul-15-97 Data Processing Method andApparatus (ART29) PO8501 Aug-11-97 Image Processing Method and Apparatus(ART30) PO8500 Aug-11-97 Image Processing Method and Apparatus (ART31)PO7987 Jul-15-97 Data Processing Method and Apparatus (ART32) PO8022Jul-15-97 Image Processing Method and Apparatus (ART33) PO8497 Aug-11-97Image Processing Method and Apparatus (ART30) PO8029 Jul-15-97 SensorCreation Method and Apparatus (ART36) PO7985 Jul-15-97 Data ProcessingMethod and Apparatus (ART37) PO8020 Jul-l5-97 Data Processing Method andApparatus (ART38) PO8023 Jul-15-97 Data Processing Method and Apparatus(ART39) PO9395 Sep-23-97 Data Processing Method and Apparatus (ART4)PO8021 Jul-15-97 Data Processing Method and Apparatus (ART40) PO8504Aug-11-97 Image Processing Method and Apparatus (ART42) PO8000 Jul-15-97Data Processing Method and Apparatus (ART43) PO7977 Jul-15-97 DataProcessing Method and Apparatus (ART44) PO7934 Jul-15-97 Data ProcessingMethod and Apparatus (ART45) PO7990 Jul-15-97 Data Processing Method andApparatus (ART46) PO8499 Aug-11-97 Image Processing Method and Apparatus(ART47) PO8502 Aug-11-97 Image Processing Method and Apparatus (ART48)PO7981 Jul-15-97 Data Processing Method and Apparatus (ART50) PO7986Jul-15-97 Data Processing Method and Apparatus (ART51) PO7983 Jul-15-97Data Processing Method and Apparatus (ART52) PO8026 Jul-15-97 ImageProcessing Method and Apparatus (ART53) PO8027 Jul-15-97 ImageProcessing Method and Apparatus (ART54) PO8028 Jul-15-97 ImageProcessing Method and Apparatus (ART56) PO9394 Sep-23-97 ImageProcessing Method and Apparatus (ART57) PO9396 Sep-23-97 Data ProcessingMethod and Apparatus (ART58) PO9397 Sep-23-97 Data Processing Method andApparatus (ART59) PO9398 Sep-23-97 Data Processing Method and Apparatus(ART60) PO9399 Sep-23-97 Data Processing Method and Apparatus (ART61)PO9400 Sep-23-97 Data Processing Method and Apparatus (ART62) PO9401Sep-23-97 Data Processing Method and Apparatus (ART63) PO9402 Sep-23-97Data Processing Method and Apparatus (ART64) PO9403 Sep-23-97 DataProcessing Method and Apparatus (ART65) PO9405 Sep-23-97 Data ProcessingMethod and Apparatus (ART66) PP0959 Dec-16-97 A Data Processing Methodand Apparatus (ART68) PP1397 Jan-19-98 A Media Device (ART69)

I claim:
 1. An ink jet printing device comprising: (a) an ink chamberhaving an oscillating ink pressure; (b) a plurality of nozzles in fluidcommunication with said ink chamber, each nozzle including a grilledshutter having an open state permitting an expulsion of ink therefromand a closed state substantially restricting an expulsion of inktherefrom; and (c) a shutter activator to drive, on demand, said grilledshutter between said open state and said closed state.
 2. An ink jetprinting device as claimed in claim 1 further including a lock adaptedto lock said grilled shutter in said open or closed state as required.3. An ink jet printing device as claimed in claim 1 wherein said shutteractivator comprises a thermocouple device.
 4. An ink jet printing deviceas claimed in claim 1 wherein said shutter activator comprises athermocouple having two arms, one of which has a thermal jacket of lowthermal conductivity.
 5. An ink jet printing device as claimed in claim4 wherein said one of said arms includes a thinned portion adapted toincrease travel of said thermocouple upon activation.
 6. An ink jetprinting device as claimed in claim 1, wherein said oscillating inkpressure can be altered in magnitude and frequency in accordance withpre-calculated factors.
 7. A method of operating an ink jet printingdevice as claimed in claim 1 so as to allow an expulsion of ink fromsaid nozzles, said method in respect of each said nozzle comprising thesteps of: opening said grilled shutter during a first high pressureperiod of said ink chamber; utilizing said high pressure period and afollowing low pressure period for the expulsion of ink from said nozzle;utilizing a subsequent high pressure period for re-filling of said inkchamber; and closing said grilled shutter until such time as further inkis required to be expelled from said nozzle.